1. Field of the Invention
This invention relates to an adhesive composition for use with rubber, and more particularly to an adhesive composition to be used for the purpose of enhancing tight adhesion between rubber and metal.
2. Description of the Related Art
This invention has bearing upon adhesive compositions formed of chlorinated type polymers.
The chlorinated type polymers comprise an adhesive polymer obtained by chlorinating natural rubber or a varying kind of synthetic rubber and a small amount of a cross-linking agent added thereto. Some of these chlorinated type polymers incorporate therein reinforcing agents such as carbon black as occasion demands. They are used for the purpose of providing adhesion between rubber and metal.
Adhesion between rubber and metal by the use of such a chlorinated type polymer as described above is attained by a method which comprises applying the adhesive polymer on the surface of rubber or metal intended for contact, then joining the rubber and the metal fast across the surface of contact, and pressing them against each other under application of heat. When this polymer is to be used in an atmosphere of elevated temperatures like a rubber vibration isolator attached to a metal housing of an automobile, a phenolic resin type primer is applied in advance on the contact surface of metal for the purpose of enhancing the tightness of adhesion between the rubber and the metal.
The chlorinated type polymer, however, deteriorates gradually on protracted exposure to the atmosphere of elevated temperatures. In spite of the use of the primer, therefore, there are times when the adhesive force gradually grows weaker to a point where separation occurs between the rubber and the metal.